Low-manganese thick Q355B steel plate and manufacturing method thereof

Abstract

The invention discloses a low-manganese thick Q355B steel plate and a manufacturing method thereof. Comprising the following components in percentage by weight: 0.19-0.22% of C, less than or equal to 0.24% of Si, less than or equal to 1.10% of Mn, 0.005-0.025% of Nb, 0.010-0.040% of Al, 0.010-0.040% of Ti, less than or equal to 0.10% of Cr, less than or equal to 0.025% of P, less than or equal to 0.008% of S, less than or equal to 0.008% of N and the balance of inevitable impurity elements. And the carbon equivalent Ceq [= C + Mn / 6 + (Cr + Mo + V) / 5 + (Cu + Ni) / 15] of the low-manganese thick Q355B steel plate is less than or equal to 0.45%. The yield strength of the steel plate is larger than or equal to 355 MPa, the tensile strength is larger than or equal to 470 MPa, the elongation (A) is larger than or equal to 21%, the Charpy impact energy at the normal temperature is larger than or equal to 54 J, and the flaw detection performance meets the II-level requirement in GB / T 2970.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgy, and in particular relates to a low-manganese-thick specification Q355B steel plate and a manufacturing method thereof. Background technique [0002] With the growth of infrastructure facilities in various countries, the demand for Q355B is increasing day by day, and it is currently the largest low-alloy structural steel produced. In the past, the Mn alloy content of 40.01-80mmQ355B steel plate was controlled at more than 1.40%. Affected by the international situation, the cost of various ores continued to rise, the price of Mn alloys continued to be high, and the production cost was relatively high. In addition, the RH process is still required for steel plates above 40mm. In fact, with the improvement of the smelting level, the cancellation of the RH process for some specifications can also meet the conventional flaw detection requirements. The decrease in the internal quality of the co...

AI Technical Summary

Problems solved by technology

In the past, the Mn alloy content of 40.01-80mm Q355B steel plate was controlled above 1.40%. Affected by the international situation, the cost of various ores continued to rise, the price of Mn alloys continued to be high, and the production cost was relatively high.

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